ESXi supports planned device removal and the detection of unplanned device loss.

Your host can determine whether a device disconnection is a temporary, all-paths-down event or whether a permanent device disconnection occurred. Planned device removal is an intentional disconnection of a storage device that uses the ability to unmount VMFS datastores. You can perform a storage reconfiguration in which you detach a datastore and later reattach it. If your host detects an unplanned device loss, ESXi marks the storage device as permanently unavailable to conserve resources and memory.

Planned device removal is a device disconnection detectable by an ESXi host. You can perform an orderly removal and reconnection of a storage device.

Unplanned device loss is a condition that occurs when your ESXi host permanently loses connection to a storage device.